L’Escargot is your stylish auntie, the one who knows how to grow old gracefully; who had that green velvet halterneck from Biba back in the day but knew when to stop wearing it. Has she surrendered to the passage of time? Hell no. She just knows exactly which version of herself to be. L’Escargot, now in its 91st year, is the same. It has been many things over the years. It has been bang on trend and it has been a survivor and now, through an acute understanding of the essentials, it is the best kind of institution. I can think of nowhere better by which to celebrate the launch of our new magazine. If you’re reading online, go pick up a print edition. It’s beautiful. Think fine old wine in new bottles. Which L’Escargot also knows a bit about, as it happens. Oh, and it does snails, obviously. I bloody love a snail.

Dig in with the tiny fork. Probe the crevices of the now empty shell with your tongue. Then get to work with bread

L’Escargot claims to have been the first place in England to offer them, if you don’t count all those hostelries serving the Roman invaders. The first version opened at the bottom of Soho’s Greek Street in 1896, as Le Bienvenue and, like Raymond Blanc, has declined to lose its French accent ever since. When it moved to its present site, in 1927, it took the name of its most popular dish and became L’Escargot Bienvenue. The owner, M Georges Gaudin, who sounds like a chap with a well-tended moustache and a fine collection of Victorian erotica, ran a snail farm in the basement.

The snails no longer come from the basement, but they are well cared for. They are served in the shell, rather than the lazy way, in a dimpled tray. Snails are all about flavour and textural fun. You need the shells, fiercely baked until the garlic-smothered parsley has started to crust. It becomes a game of accessories. If they’re not in their shells you don’t need the spring-loaded tongs – keep your wrist steady, don’t squeeze once it’s in your grip or it will fly across the room – and where’s the fun in that?

‘Do I eat it or bathe in it?’: escargot with garlic butter. Photograph: Sophia Evans for the Observer

Dig in with the tiny fork. Probe the crevices of the now empty shell with your tongue. Then get to work with torn-off pieces of bread, dredging and dredging again at the garlic butter. When my half-dozen land on the table, the tray lies under a foaming mass of melted garlic butter, the green of watercress. Do I eat it or bathe in it? Afterwards, and through the night, I will stink. I know this while eating my snails but that doesn’t stop me.

So it’s old school. To start they bring a thimble of lobster bisque, which has such a deep flavour you can’t help but wonder whether M Gaudin was the one who got the pot going back in 1927. It’s the essence of roasted shell and cognac and cream and fish stock reduced from a pint to a teacup full.

They do have a spicy crab salad to start, full of sliced fresh red chilli and lime. But even amid this self-conscious stab at modernity there is something retro about the way the brown meat has been smeared across a piece of toast. It’s a salad with a big crouton, and if a crouton is involved you can be sure the kitchen has one eye on the past.

L’Escargot is the kind of place Disney animators are imagining when they draw fancy French restaurants. The walls are painted in deep colours. They are gilded with art: a Beryl Cook print here (oh those lovely big calves); a Matisse snail cut-out there. There are chandeliers and waiters in suits and, yes, prices to wince over. But look, Soho is full of good-value ramen joints and Sri Lankan cafés and Vietnamese grill houses. Can’t we have one place where you can stick your tongue in a snail shell, order tournedos Rossini and watch your credit card bleed? For £38, it’s a sturdy, unapologetic piece of work: a thumping fillet steak cooked medium rare as requested, thick slices of black truffle, a Madeira-veal jus that you could varnish yourself with, flecked with more truffles. And, at the bottom, a crouton. We order minted peas and savoy cabbage, more to bring a bit of colour to the table than on health grounds. The lobster bisque did for that.

Toulouse sausages and mash – pommes purée, but of course – are £16 and beef bourguignon is £18. A cassoulet “au confit de canard” is a whacking plateful for £19; schedule a lie down afterwards. If I was being pedantic I would suggest it didn’t quite come across as the one-pot dish it should be, but as an assemblage of deeply sauced beans and lardons and, at the last moment, a leg of crisp-skinned confit duck under a breadcrumb crust. But it eats right. And, anyway, there’s a bottle of Provençal rosé helping it home, from a list that has never heard of any wine-producing country other than France. The rosé may not be exactly of the season, but it’s my dinner, not yours. At £28 it’s also what passes for a bargain around here.

There is a Grand Marnier soufflé offered at dessert, which is so right it’s practically a part of the order of service at a high mass. We are here to worship at the altar of classical French cuisine and we really must finish the job. It is burnished and proud and as expansive as we are beginning to feel. At the bottom it is a little loose, which is to say not entirely cooked through, but by this point in the meal we’re all a little loose in one way or another. Slap in some of the boozy Grand Marnier syrup and, really, who cares?

We are now armpit deep in every glorious Gallic cliché, and happy to be there. Oh look, here’s a crème brûlée, because it would be unthinkable to be without one. Raise the teaspoon and shout: “Look out darlings, I’m going in.” The sugar surface shatters to reveal the satin and silk of the vanilla custard below.

It is in the nature of a column like this that we are assumed to be obsessed only with the new. And there is always going to be a bit of that. But as we here at the Observer renew ourselves, it’s worth remembering that there is always a place for longevity, for commitment and for class. L’Escargot has it all.

Jay’s news bites

If you want serious old school, head to Oslo Court in London’s St John’s Wood, where the 1970s never quite ended. The tablecloths are pink, there is grilled grapefruit with brown sugar or coquille St Jacques to start, the duckling comes with sauce à l’orange, and there is a groaning ‘sweet’ trolley to finish. Three courses are £36 at lunchtime and £47 at dinner (oslocourtrestaurant.co.uk).

And here come those much-forecast brutal cold winds. The Polpo group has shuttered both its pub Ape & Bird on London’s Cambridge Circus and its Bristol outpost (open only for 18 months). All staff have been redeployed within the group. More worrying for staff is the closure of 20 – count them, 20 – branches of Byron Burger and 11 of pizza chain Strada. Expect more of this in 2018.

I bang on about non-plate serving items in restaurants for being annoying, but it turns out they can also be dangerous. A Birmingham restaurant, Ibrahim’s Grill & Steak House, has been fined £50,000 for serving food on wooden boards that were ‘incapable’ of being cleaned.